EFFECTS OF REMOVING GERM-CELLS. 23 



found. It seems probable that not all of the pole-disc granules 

 were removed in the operation and that those which were left 

 behind determined the character of the cells which encountered 

 them, the result being a smaller number of germ-cells. 



3. C. Innata, Exp. C. 3. - -This larva hatched at noon on July 

 22, exactly six days after the egg was laid. This constitutes a 

 period eight hours longer than has been computed as the average 

 time for eggs of this species. 1 Apparently very little if any delay 

 in development was caused by the operation. This larva was 

 normal in external appearance and was as active as those hatched 

 from eggs which had not been injured. It was killed when three 

 days old. No germ-glands could be discovered on sectioning, 

 but as several sections were ruined by an accident no incon- 

 testible statement as to their presence or absence can be made. 



4. C. lunata, Exp. 2a. - - This egg was laid and operated on 

 at 10 a. m. July 24 and was fixed at the expiration of twenty -two 

 hours. At this age a normal egg has a group of primordial 

 germ-cells between the vitelline membrane and the blastoderm 

 at the posterior end (Fig. 2). No germ-cells are present in the 

 operated egg ; the blastoderm cells at the posterior pole (Fig. 4) 

 are less numerous than at other points on the surface indicating 

 a delayed development in this region due to the removal of the 

 " Keimhautblastem." 



5. C. Inuata, Exp. 2,b. This egg was laid and operated on at 

 the same time as the egg in Exp. 2a. It was preserved when 

 thirty-six hours old. At this stage in uninjured eggs the germ- 

 cells are present as a group near the posterior end of the ventral 

 groove. No germ-cells were found in the operated egg but a 

 mass of yolk and cytoplasm was discovered outside of the vitel- 

 line membrane near the posterior end. 



II. THE EFFECTS OF REMOVING THE PRIMORDIAL 



GERM -CELLS. 



In two experiments on stages shown in Fig. 2 eggs were punc- 

 tured and the germ-cells allowed to flow out. The results indi- 

 cate that all of the germ-cells were not removed in every case. 



1 For an account of the life histories of these beetles see R. W. Ilegner, " Obser- 

 vations on the Bleeding Habits of three Chrysomelid Beetles, Calligrapha bigsbyana, 

 C. mitltipunctata and C. henata," Psyche, Vol. 15, pp. 21-24. 



